mirror of https://github.com/status-im/consul.git
152 lines
3.9 KiB
Go
152 lines
3.9 KiB
Go
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// Copyright (c) HashiCorp, Inc.
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// SPDX-License-Identifier: BUSL-1.1
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package dns
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import (
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"regexp"
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"strings"
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"time"
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"github.com/miekg/dns"
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"github.com/hashicorp/consul/agent/discovery"
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)
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// dnsRecordMaker creates DNS records to be used when generating
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// responses to dns requests.
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type dnsRecordMaker struct{}
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// makeSOA returns an SOA record for the given domain and config.
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func (dnsRecordMaker) makeSOA(domain string, cfg *RouterDynamicConfig) dns.RR {
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return &dns.SOA{
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Hdr: dns.RR_Header{
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Name: domain,
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Rrtype: dns.TypeSOA,
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Class: dns.ClassINET,
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// Has to be consistent with MinTTL to avoid invalidation
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Ttl: cfg.SOAConfig.Minttl,
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},
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Ns: "ns." + domain,
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Serial: uint32(time.Now().Unix()),
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Mbox: "hostmaster." + domain,
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Refresh: cfg.SOAConfig.Refresh,
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Retry: cfg.SOAConfig.Retry,
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Expire: cfg.SOAConfig.Expire,
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Minttl: cfg.SOAConfig.Minttl,
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}
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}
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// makeNS returns an NS record for the given domain and fqdn.
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func (dnsRecordMaker) makeNS(domain, fqdn string, ttl uint32) dns.RR {
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return &dns.NS{
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Hdr: dns.RR_Header{
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Name: domain,
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Rrtype: dns.TypeNS,
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Class: dns.ClassINET,
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Ttl: ttl,
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},
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Ns: fqdn,
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}
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}
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// makeIPBasedRecord returns an A or AAAA record for the given name and IP.
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// Note: we might want to pass in the Query Name here, which is used in addr. and virtual. queries
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// since there is only ever one result. Right now choosing to leave it off for simplification.
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func (dnsRecordMaker) makeIPBasedRecord(name string, addr *dnsAddress, ttl uint32) dns.RR {
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if addr.IsIPV4() {
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// check if the query type is A for IPv4 or ANY
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return &dns.A{
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Hdr: dns.RR_Header{
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Name: name,
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Rrtype: dns.TypeA,
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Class: dns.ClassINET,
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Ttl: ttl,
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},
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A: addr.IP(),
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}
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}
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return &dns.AAAA{
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Hdr: dns.RR_Header{
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Name: name,
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Rrtype: dns.TypeAAAA,
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Class: dns.ClassINET,
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Ttl: ttl,
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},
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AAAA: addr.IP(),
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}
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}
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// makeCNAME returns a CNAME record for the given name and target.
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func (dnsRecordMaker) makeCNAME(name string, target string, ttl uint32) *dns.CNAME {
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return &dns.CNAME{
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Hdr: dns.RR_Header{
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Name: name,
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Rrtype: dns.TypeCNAME,
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Class: dns.ClassINET,
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Ttl: ttl,
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},
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Target: dns.Fqdn(target),
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}
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}
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// makeSRV returns an SRV record for the given name and target.
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func (dnsRecordMaker) makeSRV(name, target string, weight uint16, ttl uint32, port *discovery.Port) *dns.SRV {
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return &dns.SRV{
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Hdr: dns.RR_Header{
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Name: name,
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Rrtype: dns.TypeSRV,
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Class: dns.ClassINET,
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Ttl: ttl,
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},
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Priority: 1,
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Weight: weight,
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Port: uint16(port.Number),
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Target: target,
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}
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}
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// makeTXT returns a TXT record for the given name and result metadata.
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func (dnsRecordMaker) makeTXT(name string, metadata map[string]string, ttl uint32) []dns.RR {
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extra := make([]dns.RR, 0, len(metadata))
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for key, value := range metadata {
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txt := value
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if !strings.HasPrefix(strings.ToLower(key), "rfc1035-") {
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txt = encodeKVasRFC1464(key, value)
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}
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extra = append(extra, &dns.TXT{
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Hdr: dns.RR_Header{
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Name: name,
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Rrtype: dns.TypeTXT,
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Class: dns.ClassINET,
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Ttl: ttl,
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},
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Txt: []string{txt},
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})
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}
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return extra
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}
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// encodeKVasRFC1464 encodes a key-value pair according to RFC1464
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func encodeKVasRFC1464(key, value string) (txt string) {
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// For details on these replacements c.f. https://www.ietf.org/rfc/rfc1464.txt
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key = strings.Replace(key, "`", "``", -1)
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key = strings.Replace(key, "=", "`=", -1)
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// Backquote the leading spaces
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leadingSpacesRE := regexp.MustCompile("^ +")
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numLeadingSpaces := len(leadingSpacesRE.FindString(key))
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key = leadingSpacesRE.ReplaceAllString(key, strings.Repeat("` ", numLeadingSpaces))
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// Backquote the trailing spaces
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numTrailingSpaces := len(trailingSpacesRE.FindString(key))
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key = trailingSpacesRE.ReplaceAllString(key, strings.Repeat("` ", numTrailingSpaces))
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value = strings.Replace(value, "`", "``", -1)
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return key + "=" + value
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}
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